Fig. 1From: Prevalence and associations of active trachoma among rural preschool children in Wadla district, northern Ethiopia: The schematic diagram of sampling procedure in selecting preschool children from rural Wadla district, northern Ethiopia, 2017. The sample size calculated was 273 using single population proportion formula, but as the sampling procedure was cluster sampling, the numbers of screened children were 596 from all 30 villages.Back to article page